#include <stdio.h>
#include <math.h>
int main()
{
	int N, T,wt[110],tmp,prewt=0;
	double valpwt[110],tmp1,ans=0;
	scanf("%d %d", &N, &T);
	for (int i = 0; i < N; i++)
	{
		scanf("%d %d",wt+i,&tmp);
		valpwt[i] = (double)tmp/wt[i];
	}
	for (int i = 0; i < N; i++)
	{
		for (int j = i+1; j < N; j++)
		{
			if (valpwt[i] < valpwt[j])
			{
				tmp1 = valpwt[i];
				valpwt[i] = valpwt[j];
				valpwt[j] = tmp1;
				tmp = wt[i];
				wt[i] = wt[j];
				wt[j] = tmp;
			}
		}
	}
	for(int i=0;i<N;i++){
		if(prewt+wt[i]<=T){
			ans+=valpwt[i]*wt[i];
			prewt+=wt[i];
		}else{
			ans+=valpwt[i]*(T-prewt);
			break;
		}
	}
	printf("%.2lf",ans);

	
}